Master object-oriented programming in C++

C is an object-oriented programming language, and object-oriented programming is a very effective way of abstracting complex systems. By using object-oriented programming techniques, we can abstract some concepts and entities in the system into classes and objects and manage them more easily. This article will introduce some basic concepts and techniques about C object-oriented programming to help you master this excellent programming paradigm.

1. Classes and Objects

In C, a class is a user-defined data type that can contain a set of member variables and member functions. Member variables are data in the class, and member functions are operations on these data. Objects are instances of this class and represent a specific implementation of the class.

For example, we can define a class to represent "car":

class Car {
public:
  int speed;
  int weight;
  void accelerate(int amount) {
    speed += amount;
  }
  void brake() {
    speed = 0;
  }
};

This class has two member variables (speed and weight) and two member functions (accelerate and brake). We can use this class to define an object:

Car myCar;
myCar.speed = 60;
myCar.weight = 2000;
myCar.accelerate(20);

Here we define an object named myCar, which is an instance of the Car class. We can use objects to access the member variables and member functions of the class, such as myCar.speed and myCar.accelerate(20).

2. Inheritance

Inheritance is an important concept in C object-oriented programming, which allows us to derive new classes from existing classes. The derived class is called a subclass and the parent class is called a base class. The subclass inherits all member functions and member variables of the base class, and can add new member functions and member variables on this basis.

For example, we can define a new class to represent a special car:

class SportsCar : public Car {
public:
  bool turbo;
};

This class is called "SportsCar" and it is derived from the base class "Car". This subclass inherits all member variables and member functions of the base class, including speed, weight, accelerate and brake, and also A new member variable turbo has been added.

Now we can create an object using this new class:

SportsCar mySportsCar;
mySportsCar.speed = 80;
mySportsCar.weight = 1700;
mySportsCar.accelerate(30);
mySportsCar.turbo = true;

Here we define an object named mySportsCar which is SportsCar Instance of class. We can use objects to access the member variables and member functions of the Car class and the SportsCar class, such as mySportsCar.speed and mySportsCar.accelerate(30).

3. Polymorphism

Polymorphism is the last concept of C object-oriented programming, which allows us to use a pointer to the parent class to refer to an object of a subclass. This is called runtime polymorphism. Polymorphism makes a program more reliable and flexible because it can choose which functions to call based on the type of object.

For example, we can define a function that accepts a pointer to a Car object as a parameter:

void drive(Car* car) {
  car->accelerate(10);
  cout << "Driving at " << car->speed << " mph." << endl;
}

This function is called drive, and it accepts a Pointer to the Car object. Inside the function we use this pointer to access the car's speed and use the acceleration function to accelerate the car.

Now we can use this function to drive the myCar object and the mySportsCar object:

drive(&myCar);
drive(&mySportsCar);

We can see that regardless of the myCar or mySportsCar, both increase their speed by 10 mph and both output the correct information. This is what runtime polymorphism does.

Summary

This article briefly introduces some basic concepts and techniques of C object-oriented programming, including classes and objects, inheritance and polymorphism. Mastering these concepts will allow you to better understand the C language and take full advantage of its object-oriented programming paradigm. If you want to learn more about object-oriented programming, check out more information or attend related training courses.

The above is the detailed content of Master object-oriented programming in C++. For more information, please follow other related articles on the PHP Chinese website!